diff options
Diffstat (limited to 'kern')
| -rw-r--r-- | kern/thread.c | 8 | ||||
| -rw-r--r-- | kern/thread.h | 8 |
2 files changed, 12 insertions, 4 deletions
diff --git a/kern/thread.c b/kern/thread.c index 785640cb..cd0717c4 100644 --- a/kern/thread.c +++ b/kern/thread.c @@ -54,7 +54,7 @@ * * A few terms are used by both papers with slightly different meanings. Here * are the definitions used in this implementation : - * - The time unit is the system timer period (1 / HZ) + * - The time unit is the system timer period (1 / tick frequency) * - Work is the amount of execution time units consumed * - Weight is the amount of execution time units allocated * - A round is the shortest period during which all threads in a run queue @@ -159,7 +159,7 @@ /* * Default time slice for real-time round-robin scheduling. */ -#define THREAD_DEFAULT_RR_TIME_SLICE (HZ / 10) +#define THREAD_DEFAULT_RR_TIME_SLICE (THREAD_TICK_FREQ / 10) /* * Maximum number of threads which can be pulled from a remote run queue @@ -170,7 +170,7 @@ /* * Delay (in ticks) between two balance attempts when a run queue is idle. */ -#define THREAD_IDLE_BALANCE_TICKS (HZ / 2) +#define THREAD_IDLE_BALANCE_TICKS (THREAD_TICK_FREQ / 2) /* * Run queue properties for real-time threads. @@ -190,7 +190,7 @@ struct thread_rt_runq { /* * Round slice base unit for fair-scheduling threads. */ -#define THREAD_FS_ROUND_SLICE_BASE (HZ / 10) +#define THREAD_FS_ROUND_SLICE_BASE (THREAD_TICK_FREQ / 10) /* * Group of threads sharing the same weight. diff --git a/kern/thread.h b/kern/thread.h index f41daefb..24e3c677 100644 --- a/kern/thread.h +++ b/kern/thread.h @@ -47,6 +47,14 @@ #include <machine/tcb.h> /* + * Scheduler tick frequency. + * + * The selected value of 200 translates to a period of 5ms, small enough to + * provide low latency, and is practical as both a dividend and divisor. + */ +#define THREAD_TICK_FREQ 200 + +/* * Thread structure. */ struct thread; |